1. Field of the Invention
The present invention relates generally to a method and apparatus for encoding control information and transmitting and receiving the control information in a wireless communication system. More particularly, the present invention relates to a method for encoding control information in a wireless communication system using Low Density Parity Check (LDPC) codes, and a method and apparatus for transmitting and receiving the control information.
2. Description of the Related Art
FIG. 1 is a diagram illustrating a transmission scheme for control information in a general wireless communication system.
Referring to FIG. 1, reference numeral 101 denotes a structure of a frame including control information that is transmitted and received in a wireless communication system. Commonly, the frame 101 includes a preamble 102, an P2-L1 signaling 103, an PLP0-L2 signaling 104, and one or more Physical Layer Pipes (PLPs) 105, 106, and 107.
The control information may be transmitted through the preamble 102, the P2-L1 signaling 103, and the PLP0-L2 signaling 104, while data may be transmitted through the PLPs 105, 106, and 107.
The preamble 102 is a signal that is generally used to acquire time and frequency synchronization, and synchronization for a frame boundary at a receiver.
The P2-L1 signaling 103 indicates a part through which an L1 signaling is transmitted. As illustrated in FIG. 1, the P2-L1 signaling 103 can also be referred to as a “P2,” because it is transmitted through P2 symbols. The P2 refers to a physical layer signaling, or a Layer 1 (L1) signaling. The physical layer signaling includes static information 108, configurable information 109, and dynamic information 110. The static information 108 includes information that is basically static over the passage of time, and such static information may include information on a cell identifier, a network identifier, the number of Radio Frequency (RF) channels, a frame length, locations of pilot subcarriers, etc. The configurable information 109 includes information that may change in the frames to be transmitted in the future, although without changing on a frame-by-frame basis. Thus, the configurable information 109 may include, for example, information on a service identifier, a modulation order used to transmit data for an individual service, a code rate, etc. The dynamic information 110 includes information that may change on a frame-by-frame basis. Such dynamic information may include information about a location where each PLP carrying service data is transmitted in the current frame, i.e. information about where each PLP starts and ends in the frame.
The PLP0-L2 signaling 104, a part through which an L2 signaling is transmitted, represents a Layer 2 (L2) or Medium Access Control (MAC) signaling. Generally, a PLP on which the L2 information is transmitted may also be referred to as a “PLP0.” The PLP0 includes connection information between PLPs and broadcast services to indicate PLPs through which particular services are received. The PLP—1 105, the PLP—2 106, and the PLP_N 107 are service data, and each of them transmits one or a plurality of broadcast service channels. These PLPs, through which actual broadcast data is transmitted, are also called “data PLPs.”
A process of actually receiving a particular broadcast service channel in a receiver of a wireless communication system is described below with reference to FIG. 1. Upon acquiring synchronization of the frame through the preamble 102, the receiver gets information on a data transmission scheme and a frame length using the P2-L1 signaling 103, obtains information indicating through which PLP a desired broadcast service channel is transmitted, using the PLP0-L2 signaling 104, and then receives data for broadcast services through the PLPs 105 to 107 carrying data.
In order to provide the services stably in the wireless communication system, transmission error of control information such as the L1 signaling and the L2 signaling should be minimized. The control information is generally encoded before transmission to minimize the transmission error. To this end, there has been a long-felt need for a scheme capable of efficiently encoding the control information.